In the field of semi-conductor fabrication, the inspection of the quality of the semi-conductor surface, as the different components and circuit layers are added, is very important. Inspections can consist in verifying that all the features of the circuit have their expected shapes and volumes. In this case, a technique, such as the Fast Moiré Interferometry (FMI), which can provide a 3D map of a surface of the object, can be used to verify the shape and volume of the circuit features. Such method offers the possibility to obtain height mapping of only one side of the semi-conductor, generally the top face on which the circuit components are laid.